Clamping device

ABSTRACT

The invention relates to a clamping device, especially for releasably clamping a machine tool having a fixing element extending therefrom. The clamping device includes a deforming clamping element which acts on a clamping part with a clamping force in order to secure the fixing element to the clamping device. The deforming clamping element may also be controlled to act on the clamping part with a releasing force in order to release the fixing element from the clamping device. Both the clamping force and the releasing force result from the deformation of the deforming clamping element.

FIELD OF THE INVENTION

The present invention relates to a clamping device, in particular formachine tools.

BACKGROUND

In machine tools of the type known to the state of the art, workpiecesare processed which can be mounted in different ways. Known are, inparticular, those devices in which the workpiece is screwed by means ofspring chucks against a machine bed and is released again by looseningthe screw accordingly. In addition, clamping devices are known, whichare screwed to the work table of the machine and are constructed orarranged specifically for a certain workpiece. When changing theworkpiece or the workpiece type, the clamping device must be dismantledand set up again each time and the zero point must again be determined.

Furthermore, the need is known for arranging and fixing severalworkpieces ideally simultaneously in the processing area of a machinetool or for removing them from there. For this purpose, the workpiecescan be arranged fixed together on a carrier, a type of pallet or thelike, in order to then fix the carrier as a whole in the processing areaof the machine tools. After completion of processing, the carrier isloosened and removed again as a whole from the fixing device.

Generally known are clamping devices in which a fixing element is usedindirectly or directly as a carrier for a workpiece that can be lockedin a receptacle. Locking or loosening is thus equivalent to the fixingor releasing of the fixing element. These clamping devices, however, arecomplicated in construction and involved in operation.

The problem of the invention is to offer a clamping device, especiallyfor machine tools, that has a simple construction for setup and issimple to operate.

SUMMARY OF THE INVENTION

The invention uses a special clamping element, which can clamp orrelease a fixing element into or out of a receptacle or a seat. In thisway, it has proven especially advantageous that very high clampingforces can be applied through relatively small actuation forces in theclamping element in order to hold the fixing element reliably. For thispurpose, the clamping element advantageously requires less installationspace and exhibits very low wear.

A simplest embodiment of the clamping element is formed in a body thatis screwed tightly, for example, to the machine bed. The body has areceptacle for inserting or removing a fixing element. The fixingelement carries the workpiece or a corresponding carrier which carriesthe workpiece or workpieces to be processed. The receptacle itself canbe constructed in a simplest case in the sense of a pot-shaped recess inthe body.

For the detachable fixing of the fixing element, the clamping deviceincludes at least one clamping element also to be described in moredetail and at least one clamping part that can receive a clamping forcefrom the clamping element. The clamping part is arranged according tothe invention so that it can move in one motion B along a clamping partmovement axis for clamping or releasing the fixing element in thereceptacle.

According to the invention, the clamping element has at least onedeformable chamber that can be pressurized with higher pressure or alower pressure. This chamber is bounded at least partially by at leastone tension-resistant or pressure-resistant wall. The chamber or thewalls are here constructed according to the invention so thatpressurization of the chamber deforms this chamber, and this deformationcauses tensile and compressive forces within the walls and especially intheir longitudinal direction. The forces appearing as such essentiallyin the longitudinal direction of the chamber walls are picked up at asuitable position (preferably at the edge of the walls) and transmittedinto the clamping part directly or indirectly, so that this clampingpart fixes or releases, on its side, the fixing element in thereceptacle.

As will be seen with reference to the description of the figures,through a clamping element constructed in this way with relativelylittle fluid-dynamic pressures in the chamber, a very high deformationforce can be generated in the chamber walls or picked up at the edgesbounding the walls in their longitudinal direction. Therefore, overallthe clamping device can have a relatively small structure andnevertheless can provide for secure holding of the fixing element in thereceptacle. As another advantage relative to the state of the art, itshould be mentioned that the clamping element can be activated withessentially any fluid, especially air, for pressurizing its chamber.Compressed air is typically available in the vicinity of the previouslymentioned machine tool or processing center, is environmentallyfriendly, and is economical.

The number of individual components of the clamping device is alsorelatively small, which overall represents a technically elegant andeconomical alternative to the known clamping devices according to thestate of the art.

An advantageous embodiment of the invention provides that thedeformation of the chamber of the clamping element generating thedeformation force is directed essentially perpendicular to thedeformation force. This effect occurs especially in chambers, in whichinner dimensions are considerably smaller than the dimensions in the twoperpendicular directions. When such a chamber is pressurized (below, theterm pressurization should also always be understood as “application” oflower pressure relative to the surroundings, in which higher pressureexists outside of the chamber), the wall regions lying at a shortdistance relative to each other are pressed apart from each other (oralso toward each other for a lower pressure). The resulting bulging thechamber leads to shortening of the chamber dimensions in at least one ofthe two longer directions by means of the tension-resistant orpressure-resistant walls. If this shortening (or lengthening for theopposite pressurization) is prevented, then a deformation forcecounteracting this change in length appears. According to the invention,the deformation force should act on the fixing element directly oroptionally transmitted as a clamping force, in order to fix it in thereceptacle or to release it in the opposite case.

The deformation force is produced according to the invention more themost part through the conversion of fluid-dynamic pressure forces withinthe chamber into forces that run along the (ideally opposing) walls andthat can be picked up at their end as tensile or compressive forces.Indeed, for pressurization, the short wall section, which connects thetwo closely adjacent walls, also experiences a corresponding compressiveforce, but the chamber according to the invention should be constructedso that this portion does not significantly contribute to the resultingdeformation force.

Ideally, the chamber consists essentially of two opposing, closelyspaced walls. Obviously, the arrangement of several such chambers in thesense of a chamber package is also conceivable, in which the walls lieessentially parallel and are joined in their end regions, so that thedeformation force can be picked up there collectively or jointly.

Another embodiment of the invention provides that at least one wall hasa convex or concave structure relative to the interior of the chamber inthe state without pressurization. Such deformed chambers also have, inthe pressure-less state, a certain basic stability and impart the extentof the change in length via the extent of the bulging, which results ina maximum when the walls are flattened by the pressurization. Accordingto the curvature and flexibility of such walls, the change in length ofthe chamber can be given relatively precisely.

It is obvious that for the previously described purpose, the walls ofthe chamber must indeed have a flexible construction, which, however, istension-resistant or pressure-resistant in their longitudinal direction,in order to transfer the forces occurring in their longitudinaldirection as unchanged as possible to the edge. In particular,constructions in the form of metal shells or several overlapping thinmetal films are conceivable. A stable, woven, preferably metallicnetwork, which is surrounded by a flexible but compact medium (forexample, a type of rubber mat with embedded steel fabric), can serve forthe previously described purpose. Obviously, any other material can alsobe used, which on the one hand has flexibility, but on the other has thenecessary stiffness and, in particular, tension and compressionresistance.

The deformation force generated by means of the clamping element shouldact according to the invention as a clamping force on the fixingelement. The deformation force is here picked up at a suitable position,especially at the edge of the adjacent chamber walls and transferred tothe clamping element. This traces the previously described motion Bbased on the change in length of the chamber and therefore allows itsshifting in the direction toward or away from the fixing element.

The resulting forces can have essentially a dual formation. First, thedeformation of the chamber itself can be used directly to convert thechange in length resulting from the deformation into a force, whichdisappears again for the reverse deformation of the chamber. Conversely,the chamber can also be somewhat biased through deformation, because thechamber walls tend toward their reverse deformation into the originalposition for sufficient stiffness. If the pressure on the chamber isagain taken away, the restoring forces force the chamber back into itsoriginal shape, wherein a clamping force results from the reversedeformation. The last variant has the advantage that for clamping nopressure medium (especially air, hydraulic oil, etc.) is required due tolack of pressurization of the chamber. This increases the security ofthe system.

In the simplest case, the deformation force generated by the clampingelement is introduced into the clamping element with the same magnitudeand in the same direction and thus corresponds to the clamping force,which guarantees an especially simple construction. However, it is alsoconceivable to increase or decrease the deformation force into theclamping force or also to change the direction. Thus, the deformationforce can be deflected, e.g., by means of a lever construction or can beconverted into a clamping force, so that the two forces enclose an angleof 90° (or another other desired angle). This enables the essentiallyflexible arrangement of the clamping element relative to the fixingelement.

In an advantageous embodiment of the invention, the clamping part has awedge surface running at an angle to the clamping force, which interactsfor the motion B with a surface of the fixing element for releasing orfixing the fixing element. Thus, if the clamping part moves, forexample, in the direction toward the fixing element, in order to clampit, then an angled wedge surface provided on the clamping part interactswith a corresponding surface of the fixing element, so that for furtheradvancing of the clamping part, the wedge surfaces transfer a motioncomponent perpendicular to the clamping force and thus move the fixingelement a certain extent along its longitudinal axis, in particular,press it and clamp it tightly in a seat or against a stop. For thereverse motion, if the clamping part is moved away from the fixingelement, the wedge surfaces releasing from each other permit a looseningof the fixing element from its clamping seat or stop. This is to be seenin detail in the description of the figures.

An especially advantageous embodiment is characterized in that thefixing element or the clamping element has an essentially rotationallysymmetric structure. For the rotationally symmetric shape of theclamping element, this can essentially surround the fixing element andcan thus apply a corresponding deformation or clamping force from allsides toward the center. The clamping element can be made from twoopposing washer rings, which essentially enclose the chamber betweenthemselves. The ring sections lying opposite each other can also beconstructed convex or concave relative to each other.

If the fixing element also has a rotationally symmetric structure, thenit can be inserted into a receptacle along its longitudinal direction inthe center of the ring-shaped clamping element and can be fixed there inprinciple independent of its rotational position. Other shapes of thefixing element are also conceivable, of course, and the clamping elementalso need not enclose the fixing element in the form of a ring. Also, anarrangement of a clamping element on only one side of the fixing elementis conceivable, in order to clamp or to loosen the fixing elementthrough the change in length of the chamber or the resulting deformationforce or clamping force.

For a ring-shaped clamping element, if the opposing chamber walls arefixed in three dimensions at the outer diameter (for example, to thebody), then the change in length takes place exclusively toward thecenter of the ring, whereby the clamping motion or clamping force canhave a very effective action from all sides on the fixing elementarranged in the center.

So that a fixing element to be fixed in the center of the clampingdevice can be successfully clamped, the clamping part arranged aroundthe fixing element can be constructed as a surrounding, slotted clampingring. Then the clamping ring can yield to the clamping forces acting onall sides from the outside to the inside under radial deformation,wherein the slot of the clamping ring narrows. Such a surrounding ringgenerates especially homogeneous clamping forces around the fixingelement, with the exception of the slotted region.

Obviously, the use of individual clamping jaws is also conceivable,which do not have to be connected to each other and which also interactin a straight, that is, uncurved, shape with a complementarily shapedfixing element.

Another embodiment of the invention provides that the clamping part isbiased against or in the direction of the clamping force. In this way,an opening or closing motion of the clamping part relative to the fixingelement is supported. Thus, for example, for a fixing element, which isarranged centrally and which is surrounded by a ring-shaped clampingelement, the clamping part features biasing against the clamping forcedirected inward. Here, if the pressure-less state of the chambercorresponds to the unclamped state of the clamping part, then the biasedclamping ring advantageously supports the opening motion. Conversely, itis of course conceivable to provide the clamping ring with biasingdirected inward in order to maintain, in principle, the clamping stateand to be expanded only through a deformation force of the clampingelement acting opposite to this clamping.

According to the invention, it can be further provided that thereceptacle holding the fixing element be equipped with a centering cone,which, for a clamping force acting on the fixing element, interacts withthis fixing element. In this way, the cone should align the fixingelement perpendicular to its longitudinal axis, while it is pressed orpulled into the clamping seat or against a stop by the clamping element.In this way it is possible, in principle, to align a fixing element tobe inserted with a certain amount of play in a desired way and to fix itthere.

An embodiment in which the centering cone is supported in a floating orspring-mounted manner for positional compensation by a predeterminedtolerance is presented as especially advantageous. Here, an alignment ofthe fixing element perpendicular to its longitudinal axis with a certaintolerance should be permitted, while the fixing element is clamped. Inthis way, changes in length, especially those due to temperaturefluctuations, can be compensated. This is especially important whenseveral clamping devices, which each hold, on their side, a fixingelement, are provided within a machine tool, wherein the fixing elementsreceive a carrier in common and therefore are connected to each other.To permit the fixed distance of the fixing elements to each other, onthe one hand, or of the clamping devices to each other, on the other,with certain tolerances, the previously mentioned centering cone isprovided with a floating or spring-mounted support. Here, it can beformed, for example, in a flexible medium embedded in the receptacle.

This can be, in particular, a sealing ring surrounding the fixingelement in which the centering cone was molded and which is insertedwith this together in the receptacle. The centering cone is then held bythe sealing ring, but can still shift slightly perpendicular to thelongitudinal axis of the fixing element.

Alternatively, the floating support can also be constructed by anessentially free end of a sleeve-shaped projection, whose opposite,fixed end is formed on or fixed to the receptacle or the body. In thiscase, the material quality or stiffness of the centering cone is thedecisive feature for its movement perpendicular to the longitudinal axisof the fixing element.

According to another advantageous embodiment of the invention, as acentering aid for a workpiece to be inserted into the receptacle withthe fixing element, at least longitudinal grooves directed over theperiphery about the longitudinal axis and running in the radialdirection are provided in the body. These interact, according to theinvention, with pins, which project from the workpiece to be fixed or aholder carrying this workpiece during the insertion into the grooves andtherefore definitely center the workpiece.

These and other advantages and features of the invention will beapparent from the following description of the preferred embodiments,considered along with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of a first embodiment of the clampingdevice according to the invention in the clamping state,

FIG. 2 is a schematic detail view according to FIG. 1,

FIG. 3 is a schematic section view of the clamping device according toFIG. 1 in the released state,

FIG. 4 is a schematic side view of a second embodiment of the clampingdevice according to the invention,

FIG. 5 is a schematic side view of two clamping devices inserted into amachine bed with a workpiece carrier arranged above,

FIG. 6 is an arrangement of four clamping devices provided in a machinebed,

FIG. 7 is a workpiece carrier connected to a fixing element withworkpiece, and

FIG. 8 is a top view of an arrangement according to FIG. 6.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

An embodiment of a clamping device according to the invention is shownin FIG. 1. In a body 3, a fixing element 2 is detachably inserted (thefixing element 2 should carry a workpiece carrier 17 indicatedschematically in FIG. 5). For this purpose, the body 3 has anapproximately pot-shaped receptacle 5 in which the fixing element 2 canbe inserted. The fixing element 2 is rotationally symmetric about itslongitudinal axis 14. It is noted that the receptacle also includes alongitudinal axis which coincides with fixing element axis 14 when thefixing element 2 is received in the receptacle 5 in the insertedposition shown in FIG. 1.

In the inserted state of the fixing element 2, it is surrounded on allsides by a clamping element 4 arranged in the body 3 and lying in itscenter. The clamping element 4 is essentially formed from two opposingring-shaped walls 8, which are slightly bent in cross section and whichmainly enclose a chamber 7 due to their convex alignment relative toeach other. The walls 8 are produced from a flexible buttension-resistant and pressure-resistant material.

The clamping element is fixed by the receptacle in the body 3 in theradial direction at the outer peripheral edge of the clamping element 4.A clamping part 6, which is connected to the walls 8, so thatdeformation of the chamber 7 or the walls 8 in the radial directionsacts inward toward the clamping part 6 in the same direction, attachesto the inward facing edges of the clamping element 4. The clamping part6 is moved in this case inward in the direction toward the fixingelement 2, so that this is fixed, as shown in detail in FIG. 2.

In FIG. 2, in an enlarged schematic partial view, the part of theclamping element 4 lying to the right of the longitudinal axis 14 isshown. The chamber 7, which is enclosed by the walls 8, can be seen,wherein the walls 8 extend essentially in a longitudinal direction L.

Pressurization of the chamber 7 with a lower pressure causes the twoopposite walls 8 to move toward each other, especially in the center ofthe chamber. Therefore, the walls 8 experience a lengthening in thehorizontal direction shown in FIG. 2, which is transferred in the formof a deformation force S in the radial direction inward directly to theclamping part 6. The deformation force S shifts the clamping part 6inward along the clamping part movement axis in a motion B. In thiscase, the deformation force S and the clamping force K are identical.

In the opposite case, for pressurization of the chamber 7 with higherpressure, the walls 8 undergo shortening in the horizontal direction,which follows the clamping part 6 in the reverse direction of the motionB, that is, directed outwardly along the clamping part movement axis.Here, the clamping part 6 can follow due to an inner biasing of thismotion to the outside from its own drive, or for suitable connection ofthe walls 8 to the clamping part 6 can also be pulled outwardly by thewalls 8 or the resulting deformation force S.

In FIG. 2, a smaller part of the fixing element 2 is further shown,which has a surface 10 at an angle relative to the motion B. Thissurface 10 interacts for the motion B with a wedge surface 9 provided onthe bottom side of the clamping part 6, such that for the motion of theclamping ring 6 in the radial direction inward, the fixing element 2 isshifted via the contact with the surface 10 by a certain extent in thedirection of its longitudinal axis 14 (also in the direction of thelongitudinal axis of the receptacle 5) or fixed at least in thisdirection against a stop (not shown).

In contrast, if the clamping element 6 is opened outwardly to asufficient extent in the radial direction, then the clamping part 6releases the section shown in FIG. 2 for the fixing element 2 in theaxial direction, so that the fixing element 2 can be completely removedupward from the receptacle 5.

While in FIG. 1 the clamped state is shown in which the clamping part 6engages behind and thus fixes a part of the fixing element 2 in thereceptacle 5, FIG. 3 shows the released state, in which the clampingpart 6 is expanded outwardly in the radial direction far enough that thefixing element 2 can be removed in the direction of its longitudinalaxis 14 upwardly from the receptacle 5. Only for the sake ofcompleteness is the chamber 7 still designated in FIG. 3.

In FIGS. 1 and 3, it can be further seen that the chamber 7 has, in theleft region of the body 3, an opening 12 for the supply of a compressedmedium for pressurization.

In FIG. 1 it can be further seen that the fixing element 2 is orientedby a centering cone 11 in an upper section. The centering cone 11 isembedded floating via a flexible sealing ring 15 in the body 3, so thata certain radial offset of the fixing element 2 relative to itslongitudinal axis 14 is possible before or during the clamping.

In FIG. 4, another embodiment of the clamping device is shown. Theclamping element 4 shown in FIG. 4 has walls 8, which lie essentiallyparallel to each other when the clamping part 6 assumes the clampedstate. Through pressurization of the chamber 7, the walls 8 are pressedapart from each other, which leads to a shortening of the walls 8 in thehorizontal direction and to a corresponding expansion of the clampingpart 6, by means of which the fixing element 2 is released.

When the clamping element 4 shown in FIG. 4 is not pressurized, itexerts a clamping effect on the fixing element 2. This fixing state thusoccurs also for an undesired loss of the pressure supply or is thenmaintained without the fixing element 2 being able to becomeunintentionally loose.

Furthermore, in FIG. 4 another form of the centering cone is to be seen.The centering cone is constructed as an upward free end of asleeve-shaped projection 16. Here, through the given stiffness of theprojection 16 (dependent on its material and its cross-sectional shape)a possible offset is realized relative to the longitudinal axis 14, inorder to receive the fixing element 2 at least within given tolerancesin a floating way.

For the sake of completeness, in FIG. 5 an arrangement of severalclamping devices according to the invention is shown. Here, fourclamping devices 1 sit in a machine bed 18 and are used for the commonholding of a pallet-shaped carrier 17. The carrier 17 is held by thefixing elements 2, which are held by each clamping device 1.Furthermore, FIG. 5 shows that the stop for the fixing element 2, whichis used for the clamping in the direction of the not-shown longitudinalaxes, is formed by the support of the carrier 17 on the body 3 of eachclamping device 1.

In FIG. 6, the arrangement according to FIG. 5 in a perspective view isshown without a carrier. FIG. 6 also shows three longitudinal grooves 19arranged over the periphery about the longitudinal axis 14 of eachclamping device. They interact according to FIG. 7 with pins 20. Thepins 20 extend from a carrier 25, which carries a workpiece 21, in thedirection toward the clamping device downward into the grooves 19 andthus center the carrier 25 relative to the clamping device 1 or thereceptacle 5. This centering is provided, in particular, where eachclamping device is to receive an “independent” fixing element, whereseveral fixing elements are arranged on a common carrier unlike carrier17 according to FIG. 5.

FIG. 8 shows four fixing elements 2, which are provided for holding acarrier plate, in a machine bed 18. Each fixing element 2 is supportedfloating, so that its absolute clamping position in the machine bed 18can be selected within given tolerances. Thus, (in particular,equivalent) heat expansions within the carrier to be inserted into themachine bed 18 are compensated, so that the carrier center always liescongruent over the center 22 of the machine bed.

As used in this disclosure and in the accompanying claims, the terms“comprising,” “including,” “carrying,” “having,” “containing,”“involving,” and the like are to be understood to be open-ended, thatis, to mean including but not limited to.

Any use of ordinal terms such as “first,” “second,” “third,” etc., inthe claims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another, or thetemporal order in which acts of a method are performed. Rather, unlessspecifically stated otherwise, such ordinal terms are used merely aslabels to distinguish one claim element having a certain name fromanother element having a same name (but for use of the ordinal term).

The above described preferred embodiments are intended to illustrate theprinciples of the invention, but not to limit the scope of theinvention. Various other embodiments and modifications to thesepreferred embodiments may be made by those skilled in the art withoutdeparting from the scope of the present invention.

The invention claimed is:
 1. A clamping device for use with a machine tool having a fixing element, the clamping device including: (a) a clamp body having a receptacle sized to receive an elongated shaft of the fixing element therein in an inserted position in which the longitudinal axis of the fixing element shaft coincides with a longitudinal axis of the receptacle, the clamp body also having at least one clamping element mounted thereon; (b) at least one clamping part in the receptacle that is (i) movable in one direction along a clamping part movement axis transverse to the longitudinal axis of the receptacle in response to a clamping force from the clamping element, and that is (ii) movable in an opposite direction along the clamping part movement axis in response to a releasing force from the clamping element; (c) the at least one clamping element including at least one deformable chamber bounded by at least one wall that is resistant to tension and pressure, the at least one deformable chamber being deformable in response to a change in pressure therein to produce a deformation force from forces running along the longitudinal axis of the at least one wall, wherein the deformation force is applied to the clamping part to produce the clamping force or the releasing force, the at least one deformable chamber also being constructed, so that, for an expansion thereof in a first direction, the cross section of the deformable chamber undergoes a change in length in a second direction perpendicular to the first direction; and (d) a contact surface on the clamping part which applies a force component in a direction parallel with the longitudinal axis of the receptacle when the clamping part is extended into the receptacle for applying the clamping force to the fixing element inserted into the receptacle.
 2. The clamping device of claim 1 wherein the change in length is a shortening.
 3. The clamping device of claim 1 wherein the deformation of the deformable chamber that results in the deformation force is directed essentially perpendicular to the deformation force.
 4. The clamping device of claim 1 wherein the at least one wall bounding the deformable chamber is constructed for converting a change of fluid-dynamic compressive forces acting perpendicular to the at least one wall into mechanical tensile or compressive forces running in the longitudinal direction of the at least one wall.
 5. The clamping device of claim 1 wherein the deformable chamber is bounded by two opposing walls.
 6. The clamping device of claim 1 wherein the at least one wall has a convex or concave curvature relative to the interior of the deformable chamber when the deformable chamber is in an unpressurized condition.
 7. The clamping device of claim 1 wherein the contact surface of the clamping part comprises a wedge surface which runs at an angle to the direction of the clamping force and faces into the receptacle.
 8. The clamping device of claim 1 wherein the clamping element has a rotationally symmetric structure about the longitudinal axis of the receptacle.
 9. The clamping device of claim 8 wherein the clamping force is directed inward in a radial direction toward the longitudinal axis of the receptacle.
 10. The clamping device of claim 1 wherein the clamping part comprises a slotted clamping ring surrounding the receptacle.
 11. The clamping device of claim 1 wherein the clamping part is biased in the direction of the clamping force or the releasing force.
 12. The clamping device of claim 1 further including a centering cone within the receptacle in position to apply a centering force to the fixing element inwardly toward the longitudinal axis of the receptacle.
 13. The clamping device of claim 12 wherein the centering cone is supported for movement in a predetermined amount perpendicular to, and away from, the longitudinal axis of the receptacle.
 14. The clamping device of claim 13 wherein the centering cone is supported in a flexible medium embedded in the receptacle.
 15. The clamping device of claim 13 wherein the centering cone comprises a distal end of a sleeve projection whose opposite end is fixed relative to the receptacle.
 16. The clamping device of claim 1 wherein the clamp body has at least three elongated grooves formed in an outer surface thereof and extending radially from the longitudinal axis of the receptacle.
 17. A clamping system including: (a) a fixing element secured to a structure which is to be securely and releasably clamped in position, the fixing element including an elongated shaft extending from the structure; (b) a clamp body having a receptacle sized to receive the elongated shaft of the fixing element therein in an inserted position in which the longitudinal axis of the fixing element shaft coincides with a longitudinal axis of the receptacle; (c) a clamping element mounted on the clamp body; (d) a clamping part that is (i) movable into the receptacle in a clamping direction along a clamping part movement axis transverse to the longitudinal axis of the receptacle in response to a clamping force from the clamping element, and that is (ii) movable in an opposite direction along the clamping part movement axis in response to a releasing force from the clamping element; (e) the clamping element including a deformable chamber and wall structure, the deformable chamber and wall structure being deformable in response to a change in pressure in a chamber therein to produce a deformation force applied to the clamping part to produce the clamping force or the releasing force, the chamber and wall structure also being constructed, so that, for an expansion of the chamber therein in a first direction, the cross section of the chamber undergoes a change in length in a second direction perpendicular to the first direction; and (f) a contact surface on the clamping part which applies a force component in a direction parallel with the longitudinal axis of the receptacle when the clamping part is extended into the receptacle for applying the clamping force to the fixing element inserted into the receptacle.
 18. The clamping device of claim 1 further including a centering cone within the receptacle in position to apply a centering force to the fixing element inwardly toward the longitudinal axis of the receptacle.
 19. The clamping device of claim 18 wherein the centering cone is supported in a flexible medium embedded in the receptacle.
 20. The clamping device of claim 18 wherein the centering cone comprises a distal end of a projection sleeve whose opposite end is fixed relative to the receptacle. 